Solar UV Doses of Young Americans and Vitamin D3 Production

摘要

Background: Sunlight contains ultraviolet B (UVB) radiation (290–315 nm) that affects human health in both detrimental (skin cancers) and beneficial (vitamin D₃) ways. Serum 25-hydroxyvitamin D concentrations from young Americans (≤ 19 years) show that many have deficient (3 (~ 1,000 IU/day) from their “casual,” or everyday, outdoor exposures even if they diligently use sunscreens with sun protection factor (SPF) 15. Objective: We estimated how much vitamin D₃ young Americans ( n = ~ 2,000) produce from their everyday outdoor ultraviolet doses in the North (45°N) and South (35°N) each season of the year with and without vacationing. Methods: For these vitamin D₃ calculations, we used geometric conversion factors that change planar to whole-body doses, which previous calculations did not incorporate. Results: Our estimates suggest that American children may not be getting adequate outdoor UVB exposures to satisfy their vitamin D₃ needs all year, except some Caucasians during the summer if they do not diligently wear sunscreens except during beach vacations. Conclusion: These estimates suggest that most American children may not be going outside enough to meet their minimal (~ 600 IU/day) or optimal (≥ 1,200 IU/day) vitamin D requirements.